The long term cognitive impairment is well described in patients admitted in the ICU. A recent study followed-up the patients subjected to mechanical ventilator who had developed delirium. They use the Mini-mental State Examination Score and they found that at 3 month following-up 61% patients had severe cognitive impairment and 17% a moderate impairment. At 12 months the 36% of patients still had a severe impairment and the 35% a moderate impairment. The developing of delirium during the ICU admission is considered a risk factor for long term cognitive impairment.